Screenshots for storyboards?

Is it acceptable to post screenshots under the sketch heading to illustrate the final output of an original storyboard? I've seen screenshots in various places under Rubberslug, and while it seems to be a technical violation of the rules, it also seems to be allowed in practice in relation to original pieces. And in people's logos, of course.
But I'd like to get a more official OK before I do it.

Yeah, people do that a lot I think. Go right ahead. Thanks for asking.